Flexible display apparatus including dummy pattern between wirings

ABSTRACT

A flexible display apparatus includes a flexible substrate having an active area and an inactive area, the inactive area including a first area adjacent to the active area, a second area in which a pad is disposed, and a bending area disposed between the first area and the second area, wherein a plurality of wirings extending from the second area to the first area are disposed in the bending area, and at least one dummy pattern is in between the plurality of wirings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/112,397, filed on Dec. 4, 2020, which claims priority from KoreanPatent Application No. 10-2019-0165217, filed on Dec. 12, 2019, whichare hereby incorporated by reference in their entirety for all purposesas if fully set forth herein.

BACKGROUND Field of the Disclosure

The present disclosure relates to a flexible display apparatus, and moreparticularly, to a flexible display apparatus having a bendable displaypanel.

Description of the Background

Along with the recent advent of the information age, the displaytechnology for expressing electrical information signals into visualimages has rapidly developed. Consequently, a variety of displayapparatuses with excellent performance in effecting thinner design,weight lightening, and lower-power consumption are currently underdevelopment.

Specific examples of such a display apparatus may include a liquidcrystal display apparatus (LCD), an organic light emitting displayapparatus (OLED), a quantum dot display apparatus and so on.

This display apparatus may include a display panel and a number ofcomponents for providing various functions. For example, one or moredisplay driving circuits for controlling the display panel may beincluded in a display assembly. Examples of driving circuits may includegate drivers, light emitting (source) drivers, power (VDD) routing,electrostatic discharge (ESD) circuits, multiplex (MUX) circuits, datasignal lines, cathode contacts, and other functional elements. Aplurality of peripheral circuits for providing various types ofadditional functions, such as, for example, touch sensing or fingerprintidentification or other functions, may be included in the displayassembly. Some components may be disposed on the display panel itself,or on some areas adjacent to the display area, which is a non-displayarea and/or an inactive or non-active area.

The dimension and weight of a display apparatus may be one of the mostimportant issues when designing such a display apparatus. Further, ahigh ratio of the size of the active area to the size of the inactivearea, typically referred to as a screen-to-bezel ratio, may be one ofthe main characteristics in the state of the art. However, arrangingsome of the aforementioned components in one display assembly mayrequire a large inactive area, which may often add up to much part ofthe display panel. The larger inactive area generally tends to make thedisplay panel larger, which typically makes it difficult to integratethe display panel into a housing of the display apparatus. The largerinactive area may require a larger masking (e.g., bezel edge, coveringmaterial, etc.) to cover a large portion of the display panel, and insome cases, it may lead to a problem that disadvantageously affects theaesthetic feelings of the display apparatus.

Some components may be disposed on a separate flexible printed circuitboard (FPCB) and/or may be located on the backplane of the displaypanel. However, notwithstanding this configuration, interfaces forconnecting wirings between the FPCB and any active area or thosecomponents necessary for driving a display panel such as a driver IC arestill disposed in the inactive region, which may result in a limitationin reducing the bezel dimension.

SUMMARY

The inventors of the present disclosure have recognized that a varietyof high technologies such as, for example, the location of the wiring,the width of the wiring, and a signal transmission scheme are requiredto implement a narrow bezel with a reduced size of inactive area.Accordingly, the inventors of the present disclosure have carried outvarious studies utilizing the bending characteristics of a displayapparatus to which a flexible substrate is applied. Through thoseseveral studies, the inventors have devised a novel structure and amanufacturing method for minimizing a non-display area, for example, aninactive area, which is not an active area where images are displayed.

For example, the proportion of the active area can be increased bybending part of the display panel, in order to make the displayapparatus smaller and lighter by lowering the proportion of the inactivearea. This allows some inactive area to be located behind the activearea of the display panel, and thus, it can reduces or eliminates theinactive area that has to be hidden beneath a masking or a housing ofthe display apparatus. Such bending of the display panel provide aflexible display apparatus capable of minimizing the dimension of aninactive area to be concealed from the field of view, realizing a narrowbezel or a bezel-free display apparatus, and improving aestheticfeeling.

However, there have been yet new challenges to be solved when providingsuch flexible display panels.

For bending of the flexible substrate, polyimide was used for thesubstrate, and a wiring was then formed without a separate inorganicinsulating film in the to-be-bended area to prevent occurrence ofcracking. In case where such a separate inorganic insulating film isformed beneath the wiring of the to-be-bended area, the bended area areoften subject to various mechanical stresses and environmental stressesthat may occur during its manufacturing stage and/or in its using aftercompletion of the product. The stress generated due to thecharacteristic hard properties of the inorganic insulating film maybreak the inorganic insulating film. In particular, the mechanicalstress from the bending process of the flexible display panel may tendto disadvantageously affect the reliability of the product or,furthermore, cause failure of the finished components. For example,wiring-related components such as a high-potential voltage (VDD) wiring,a low-potential voltage (VSS) wiring, and data signal lines that extendfrom the inactive area and then formed in the to-be-bended area havebeen designed to minimize the cracks that may occur in the inorganicinsulating film, by forming them without any inorganic insulating filmbetween the components and the flexible substrate. An interaction ofchlorine gas (Cl) used when performing dry etching to form a wiring inthe bending region, and the residual films existing on the substrate maycause reaction with the wiring to generate oxidation. This oxidation maygrow gradually over time to become a so-called dark spot, and oftengenerate cracks or shorts in the wiring to cause some quality problems.Hereinafter, for the sake of convenience, such a to-be-bonded area ofthe flexible substrate will be referred to as a “bending area” or a“bending section”.

Therefore, it will be a key point in realizing such a narrow bezel orbezel-free display apparatus to design the bending area so as not toundergo oxidation of its wiring, without reinforcing by additionalfixtures, to prevent disconnection or short-circuit of the wiring,thereby ensuring not to go against the prevailing development trends forthe state of the art flexible display apparatus, that is, the lighterweight and thinner dimension.

A display apparatus according to aspects of the present disclosurecomprises a flexible substrate having an active area and an inactivearea, the inactive area including a first area adjacent to the activearea, a second area in which a pad is disposed, and a bending areadisposed between the first area and the second area, wherein a pluralityof wirings extending from the second area to the first area may bedisposed in the bending area, and a dummy pattern may be in between theplurality of wirings.

A display apparatus according to aspects of the present disclosurecomprises a substrate having a display area and a non-display area, thenon-display area including a first area, a second area and a bendingarea disposed between the first area and the second area, the bendingarea including a plurality of first wirings extending to the first areaand the second area, and a dummy pattern extending in the same directionas the first wiring between the plurality of first wirings.

Details of other aspects are included in the detailed description anddrawings as disclosed herein.

A display apparatus according to the exemplary aspects of the presentdisclosure is possible to provide a display apparatus with a slim bezelor narrow bezel in an overall appearance of a display panel, by applyinga flexible substrate to fold all or part of an inactive area, which is anon-display area of the display panel, in a form having a certain radiusof curvature, and arranging it on the rear surface of the active area.

Therefore, a user of this display apparatus can enjoy a deviceaesthetically full of the light emitting screen on the entire frontsurface of the display apparatus, and the display apparatus can renderthe user experiencing better feeling of grip and lighter weight, byusing a compact module applied to a narrow bezel functionally.

The display apparatus according to the exemplary aspect of the presentdisclosure may be configured to dispose a dummy pattern between thewirings to prevent oxidation of the various wirings disposed on asubstrate region to be bent, when all or part of the inactive region isfolded into the form having a certain radius of curvature so that thedistance between the substrates gets to a certain thickness. Such adummy pattern may prevent chlorine gas (Cl gas) used in the dry etchingprocess performed to finish the shape of the wirings from remaining in aspace formed in between the wirings in the bending area. Adding thedummy pattern to the space formed in between the wirings in the bendingarea so that there is no room for chlorine gas to remain enables toprevent oxidation of the wirings efficiently.

The display apparatus according to the exemplary aspects of the presentdisclosure makes it possible to prevent increased oxidation of thewirings as the isolation distance or spacing between those wirings getslarger, by arranging a plurality of dummy patterns along the extendingdirection of the wirings.

The display apparatus according to the exemplary aspects of the presentdisclosure makes it possible to arrange the distance between theplurality of dummy patterns and adjacent wirings at regular intervals tomake a control of the space where oxidation can occur.

The display apparatus according to an exemplary aspect of the presentdisclosure can keep constant or reduce the stress applied to neighboringwirings in the process of bending the flexible substrate by arrangingthe dummy patterns in a certain regular form.

The display apparatus according to the aspects of the present disclosurecan improve the durability of the bending area by optimizing thearrangement of the structure disposed in the bending area to keepconstant the tensile stress and the compressive stress applied to thestructure.

The effects of the present disclosure are not limited only to theforegoing, and other effects not disclosed herein will be clearlyunderstood by those skilled in the art from the following description.

All the contents as disclosed heretofore with reference to the subjectmatter(s) to be solved, the solution for solving the problems, and theeffects of the disclosure do not specify the essential features of theclaims, and the scope of the claims should not be construed to belimited by the contents of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate aspects of the disclosure andtogether with the description serve to explain various principles of thepresent disclosure.

In the drawings:

FIG. 1 shows a top view of a display panel according to an exemplaryaspect of the present disclosure;

FIG. 2 shows a cross-sectional view taken along cutting line I-I′ ofFIG. 1 .

FIG. 3 shows an enlarged cross-sectional view of dotted line area II ofFIG. 1 ;

FIG. 4 shows an enlarged view of a bending area in which the cuttingsection of FIG. 2 is bent;

FIG. 5 schematically shows a sequence of stages in which the oxides aregenerated in the first wiring according to an exemplary aspect of thepresent disclosure;

FIG. 6 shows an enlarged plan view of the wiring and its neighboringelements formed on a substrate in the bending area; and

FIG. 7 is a cross-sectional view of the wirings taken along cutting lineof FIG. 6 .

DETAILED DESCRIPTION

Advantages and features of the present disclosure, and methods forachieving the same may be apparent from the aspects described below withreference to the accompanying drawings. However, the present disclosureis not limited to the aspects disclosed herein, and various changes maybe made thereto. The aspects disclosed herein are provided only toinform one of ordinary skilled in the art of the category of the presentdisclosure. The present disclosure is defined only by the appendedclaims.

The shapes, sizes, ratios, angles, and numbers shown in the drawings todescribe aspects of the present disclosure are merely examples, and thepresent disclosure is not limited thereto. The same reference numeraldenotes the same element throughout the specification. When determinedto make the subject matter of the present disclosure unnecessarilyunclear, the detailed description of the known art or functions may beskipped. The terms “comprises” and/or “comprising,” “has” and/or“having,” or “includes” and/or “including” when used in thisspecification specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise.

An element is interpreted as having a margin of error unless expresslystated otherwise.

It will be understood that when an element is referred to as beingpositioned or located “on,” “over,” “under,” or “next to” anotherelement, intervening elements may be present between the two elementsunless referred to as being positioned or located “directly on,”“directly over,” “directly under,” or “directly next to” anotherelement.

It will be understood that when an event is referred to as occurring“after,” “subsequent to,” “next to,” or “before” another event, it mayoccur discontinuously from the other event unless referred to asoccurring “directly after,” “directly subsequent to,” “directly nextto,” or “directly before” or “immediately after,” “immediatelysubsequent to,” “immediately next to,” or “immediately before.”

Although the terms “first” and “second” are used to describe variouscomponents, the components are not limited by the terms. These terms areprovided simply to distinguish one component from another. Accordingly,the first component mentioned herein may also be the second componentwithin the technical spirit of the present disclosure.

Such denotations as “first,” “second,” “A,” “B,” “(a),” and “(b),” maybe used in describing the components of the present disclosure. Thesedenotations are provided merely to distinguish a component from another,and the essence of the components is not limited by the denotations inlight of order or sequence. When a component is described as“connected,” “coupled,” or “linked” to another component, the componentmay be directly connected or linked to the other component, but itshould also be appreciated that other components may be “connected,”“coupled,” or “linked” between the components.

As used herein, the term “display apparatus” may be interpreted asencompassing liquid crystal modules (LCMs), organic light emitting diode(OLED) modules, or quantum dot (QD) modules including a display paneland a driver for driving the display panel. The term “display apparatus”may also encompass complete or final products including an LCM, OLEDmodule, or QD module, such as laptop computers, televisions, computermonitors, automotive displays, vehicle equipment displays, smartphones,electronic pads, or other mobile electronic devices, or such setelectronic devices, or set devices or apparatuses.

The term “display apparatus” may encompass LCMs, OLED modules, QDmodules, or other display apparatuses or application products orconsumer devices or set devices equipped with an LCM, OLED module, or QDmodule.

In some cases, an LCM, OLED module, or QD module including a displaypanel and a driver may be referred to as a “display apparatus,” or anelectronic device, as a complete product including an LCM, OLED module,or QD module, may be referred to as a “set device.” For example, thedisplay apparatus may include a display panel of liquid crystal display(LCD), OLED, or QD and a source printed circuit board (PCB), as acontroller for driving the display panel, and the set device may furtherinclude a set PCB, as a set controller electrically connected with thesource PCB to control the entire set device.

As used herein, the term “display panel” may encompass all kinds ortypes of display panels including LCD panels, OLED panels, QD displaypanels, and electroluminescent display panels and is not limited tospecific display panels that have an OLED display panel flexible boardand a backplay supporting structure thereunder and are bezel-bendable.The display panel used in a display apparatus according to an aspect ofthe disclosure is not limited to a specific shape or size.

Specifically, where the display panel is an OLED display panel, thedisplay panel may include multiple gate lines, multiple data lines, andpixels at the intersections of the gate lines and the data lines. Thedisplay panel may include an array including a thin film transistor(TFT) to selectively apply voltage to each pixel, an OLED layer on thearray, and an encapsulation substrate or layer on the array to cover theOLED layer. The encapsulation layer may protect the TFT and OLED layerfrom external impacts and prevent infiltration of moisture or oxygeninto the OLED layer. Layers formed on the array may include, e.g., aninorganic light emitting layer, e.g., a nano-sized material layer or aQD layer.

In the present disclosure, FIG. 1 illustrates an exemplary organicelectroluminescent (OLED) display panel 100 that may be incorporatedinto display apparatuses.

FIG. 1 shows a top view of the display panel according to an exemplaryaspect of the present disclosure. Referring to FIG. 1 , the organicelectroluminescent display panel 100 may include at least one activearea AA in which light emitting elements and an array for driving thelight emitting elements are formed.

The display panel 100 may include an inactive area IA disposed in theperiphery of the active area AA, wherein the top, bottom, left, andright peripheral portions out of the active area AA may be referred toas an inactive area IA. For example, in the bottom peripheral portion,the inactive area IA may include a first area F/A adjacent to the activearea AA, a second area S/A in which a pad 135 is disposed, and a bendingarea B/A disposed between the first area F/A and the second area S/A.Although the active area AA may have a rectangular shape, various othershapes of display devices such as a circle, an ellipse, or a polygon maybe applied to a smart watch, an automotive display device and so on.Therefore, the arrangement of the inactive area IA surrounding theactive area AA is not limited to the organic electroluminescent (OLED)display panel 100 illustrated in FIG. 1 . In the left and right inactiveareas IA out of the active area AA, various components for driving thelight emitting elements and arrays formed in the active area AA may bepositioned to provide a function for stable light emission. For example,these components may include circuits such as gate-in-panel (GIP) 123),electrostatic discharge (ESD) 124 and other, an area for contactingbetween a cathode that is part of a light emitting element and a lowpotential voltage (VSS) wiring 122 that is a voltage reference point ofthe light emitting element, and a number of dam structures to preventthe overflow out of the display panel 100 during the coating process ofa foreign matter compensation layer of an encapsulation layer 170 forprotecting the light emitting element from external moisture or foreignsubstance. Further, a crack stopper structure 126 may be disposed in theinactive area, for preventing cracks from being spread into the displaypanel 100, which cracks may occur during the cutting process (namely,scribing process) to divide a mother substrate into some separatedisplay panels 100.

The crack stopper structure 126 of the present disclosure can preventgrowing of a dark spot or generation of pixel shrinkage, as the impactgenerated by the trimming line of the substrate 110 during the cuttingprocess gets to GIP 123, ESD 124 or the low-potential voltage (VSS)wiring 122 formed in the inactive region IA to destroy the same, or itprovides a moisture-permeable path to the light-emitting element orarray formed in the active region AA.

The crack stopper structure 126 may be formed of an inorganic film or anorganic film, and may be formed of a multilayer structure of theinorganic film and the organic film, although it is not limited thereto.Although FIG. 1 illustrates that the crack stopper structure 126 is onlydisposed on both the longer side and one shorter side of the displaypanel 100, it is not limited thereto. For example, the crack stopperstructure 126 may be also disposed in the bending area BA and the areawhere the notch 151 is formed, so that it may be disposed onsubstantially the entire outer surface region of the substrate 110.

In the area adjacent to the trimming line of the substrate 110, whichcorresponds to the outside of the crack stopper structure 126, it ispossible to etch part or the whole of the insulating films (GI, bufferlayer, etc.) entirely deposited when forming the active region AA.Through such etching, a small amount of insulating film may remain onthe upper portion of the substrate 110 or the upper surface of thesubstrate may be completely exposed, so that no impact of the cutting istransmitted to the corresponding insulating film.

Referring back to FIG. 1 , an FPCB electrically connected to a pad 135configured to receive/transmit a touch signal or to receive an externalpower and a data driving signal may be disposed in a lower area of thedisplay panel 100. A wiring 121 for high potential voltage (VDD), awiring 122 for low potential voltage (VSS), and/or a voltage wiring 127for data extending from the FPCB may be disposed.

The voltage wiring 127 for data of the present disclosure may bedisposed to be connected to a data driver Integrated Circuit IC thatgenerates a light emission signal from the light emitting element 112.

The area where the pad 135 and the data driver integrated circuit IC asdescribed above are disposed may be of a second component formingsection. A portion of the high potential voltage wiring 121 and the lowpotential voltage wiring 122 may be disposed in the second componentforming section.

Referring to FIG. 1 , a notch 151 formed by cutting both the lower edgesof the display panel 100 for bending the bending area BA, as indicatedby a dotted line, may be arranged in the display panel 100 according toan aspect of the present disclosure.

For example, when performing the cutting process for dividing the mothersubstrate into individual display panels, some of the inactive area IAmay be cut inwardly in the vicinity of both the lower edge areas of thedisplay panel 100, which is part of the inactive area IA. Thus, thenotch 151 may be formed such that the trimming line is adjacent to thewiring 121 for high-potential voltage (VDD) or the wiring 122 forlow-potential voltage (VSS).

The notch 151 of the present disclosure may be disposed so that it maystart at one end of the flexible substrate 110 and the bending processmay be performed in the vicinity of the corresponding area. The bendingprocess may be terminated may be adapted to end in the vicinity of thedata driver integrated circuit IC 137, so that the flexible substratearea with the data driver integrated circuit IC and the FPCB pad 135 mayabut onto a back side of the flexible substrate 110 on which the activearea AA is formed.

The member connected to the pad 135 formed on the top surface of thedisplay panel 100 is not limited to the FPCB, and various members can beconnected, and the position of the pad 135 may be disposed on the topsurface or back surface of the display panel 100 as circumstancesrequire.

Although FIG. 1 illustrates that the data driver IC is arranged on theupper surface of the display panel 100, the arrangement is not limitedto the data driver IC. Further, the location of the data driver IC isnot limited to the upper surface of the display panel and it may bedisposed on its back surface.

FIG. 2 is a cross-sectional view taken along cutting line I-I′ shown inFIG. 1 , in order to emphasize a cross-section of a state in which theinactive area IA of the display panel 100 in FIG. 1 is bent. In FIG. 2is illustrated the active area AA including a flexible substrate 110,and a TFT, a light emitting element and an encapsulation layer 170 thatmay be formed on the flexible substrate 110.

The flexible substrate 110 may be, for example, a polyimide resin-basedmaterial, although not limited thereto. A buffer layer 111 may be formedon the flexible substrate 110 and an active layer ACT may be thenformed. The buffer layer 111 may have a structure in which a pluralityof inorganic insulating layers such as SiNx and SiOx are stacked, butthe structure is not limited thereto. The active layer ACT may be formedof low temperature polysilicon (LTPS), and a gate insulating layer 120may be disposed on the active layer ACT. A gate layer GE may be formedon the gate insulating layer 120, which gate layer GE may be formed ofmolybdenum (Mo). An interlayer insulating layer 130 may be formed on thegate layer GE, and a hole may be formed through the gate insulatinglayer 120 and the interlayer insulating layer 130 to connect a sourceelectrode SE and a drain electrode DE of the TFT to the active layerACT. A first planarization layer 150 and a second planarization layer160 may be disposed on the source electrode SE and the drain electrodeDE. This planarization film may be formed of an organic film. An anodeelectrode AD, an organic emission layer EL for light emission, and acathode electrode CD may be formed on the second planarization layer160.

On the cathode electrode CD may be formed an encapsulation layer 170 toprotect the organic light emitting layer EL from external moisture orforeign matter. The encapsulation layer 170 may have, for example, athree-layer structure of inorganic film/organic film/inorganic film, andthe inorganic film may be of e.g., Si-based SiNx, SiOx, or SiON.

The organic film applied to the encapsulation layer 170 may be aparticle capping layer (PCL), but it is not limited to such a term. Theparticle capping layer may be formed of a material such as e.g., epoxyresin, which is of a polymer. In case of the inorganic film, aninorganic material made up of a plurality of layers, such as e.g.,SiNx/SiON, rather than a single layer, may be used.

The bending area BA may be disposed in the inactive area IA, which is anarea surrounding the active area AA, and a micro coating layer 360 (MCL)may be then disposed above the substrate 110 corresponding to thebending area BA, so as to prevent various wirings disposed on thebending area BA from being cut and damaged.

The micro coating layer 360 may be disposed on various wirings such as adata wiring 127, a high potential voltage wiring 121, and a lowpotential voltage wiring 122 formed on the bending area BA, so that thepositions of these wirings in the bending can be adjusted to get closerto the neutral line. Hence, the durability of the wirings can be furtherimproved by allowing the tensile stress formed above the neutral lineand the contraction stress formed beneath the neutral line to be appliedto those wirings as small as possible. In addition, the micro coatinglayer 360 may also include physical and/or chemical protection functionscapable of protecting various wirings 310 disposed on the flexiblesubstrate 110 from external impact, moisture, or dust during themanufacturing process.

FIG. 3 shows an enlarged view of the area where the notch 151 of FIG. 1is disposed, showing various components in the bending area BA and theinactive area IA before performing the bending process.

The notch 151 can be made by inwardly cutting an edge of the flexiblesubstrate 110 at a position corresponding to the bending area BA, whichis folded to the back surface of the substrate 110 upon bending in theinactive area IA. The substrate cutting line as shown in FIG. 3 may beformed by a substrate cutting method using a laser. For a slim or narrowbezel, the smaller being the area of the substrate 110 to be bent whenperforming the bending process, the smaller becomes the stress appliedto the substrate 110 in the bending, so that processability can befurther improved. In addition, a crack stopper structure 126 may beformed inside the substrate 110 along the trimming line including thenotch 151 to prevent propagation of cracks that may occur during thecutting process. As shown in FIG. 3 , the trimming line of the substrate110 may be formed with round corners to improve processability anddurability.

The GIP 123, the ESD 124 and so on may be disposed on a side surface ofthe active area AA, and the low potential voltage wiring 122 forgrounding may be disposed along the outer periphery. The external powerinput from the pad 135 may pass through the bending area BA via the highpotential voltage wiring 121, the data wiring 127, and the gate powerline 125, and enter the active region IA which is close to the activearea AA. Further, the data wiring 127 may extend from a driver IC topass through the bending area BA and then enter the active area AA. Byconfiguring the various wirings to pass through the bending area BA,most of those wirings may be subject to the tensile stress andcontraction stress during the bending process. Thus, when the bendingarea BA is bent with a radius of curvature (R) smaller than a designvalue that the wirings passing through the bending area BA can endure,the stress may be concentrated on part of the wiring corresponding tothe radius of curvature smaller than the design value, thereby causingdamage of the wiring. As a result, a structural defect may occur thatthe display panel 100 does not work properly.

Therefore, in order to protect the wirings of the bending area BA, itwill be important to configure the flexible substrate 110 to have acertain radius of curvature R so as to prevent some of the wirings frombeing deformed due to additional external force.

FIG. 4 is a cross-sectional view showing the structure when the bendingof the display panel 100 has been completed. For convenience ofillustration, in FIG. 4 , the TFT array and the light emitting elementformed on the flexible substrate 110 are indicated by a flat active areaAA, and the encapsulation layer 170 may be of a threefold layer of e.g.,an inorganic film/organic film/inorganic film covering the top surfaceof the active area AA and the side surface of the bending area BA, butthe configuration of the encapsulation layer is not limited thereto.

A touch electrode layer 181 for recognizing touch and a first adhesivelayer may be disposed in the active area AA. The touch electrode layer181 may adopt, for example, an electrostatic touch or force touch methodcapable of sensing a touch pressure, or a pen touch method using a pen,although it is not limited thereto.

A polarization layer 182 may be disposed on the touch electrode layer181 according to the aspect of the present disclosure. The polarizationlayer 182 may be adapted to minimize the influence that light generatedfrom an external light source may enter the display panel 100 to affectthe active area AA. The aspect of the present disclosure is not limitedto the structure as disclosed in FIG. 4 . For example, for any productsvery sensitive to the touch sensitivity, the touch electrode layer 181and the polarization layer 182 may be disposed in a different order.

According to the exemplary aspect of the present disclosure, a secondadhesive layer 183 may be disposed on the polarizing layer 182. A coverwindow 190 may be then attached to the outside of the display panel 100to protect the display panel 100 from the external environment. Thecover window 190 may be of a cover glass, a cover member, and the like,and it is not limited only to these terms.

A support layer 116 may be disposed underneath the flexible substrate110 and a second touch electrode layer may be disposed underneath thesupport layer 116. The support layer 116 may be made of, for example,polyethylene terephthalate (PET), but it is not limited thereto. In thesecond touch electrode layer, a second sensor layer for the force touchsensing for sensing a touch pressure or an electromagnetic sensing touchfor recognizing the touch by a pen may be disposed underneath theflexible substrate 110.

A metal layer may be further disposed beneath the support layer 116 orbeneath the second touch electrode layer. Noise may be generated inbatteries or semiconductor chips of the module to which the displaypanel 100 is attached, and the noise may cause electromagneticinterference (EMI) in the display panel 100. Then, such electromagneticinterference may cause a malfunction of the thin film transistor or theorganic light emitting diode (OLED) of the active layer 101 or anabnormality of the display screen of the display panel. To prevent them,for example, a metal layer having a thickness of about 0.1 mm may bedisposed, so that the electromagnetic interference (EMT) can be blocked.Alternatively, arranging the metal layer enables to have a heatdissipation effect dispersing heat generated from the light source ofthe display panel 100 as well as a strengthening effect capable ofsupporting the flexible substrate 110 more firmly.

An adhesive layer 118 may be disposed between the bent flexiblesubstrate 110. The adhesive layer 118 may be disposed under the supportlayer 116 to maintain a bent shape of the flexible substrate 110. Forexample, the adhesive layer 118 may be a double-sided adhesive layer.For example, the double-sided adhesive layer may include a foam tape, apressure sensitive adhesive, a foam-type adhesive, a liquid adhesive, aphoto-curing adhesive, or any other suitable adhesive component. Theadhesive layer 118 may be formed of or include a compressive material,and the compressive material may be a cushion for portions bonded to theadhesive layer 118. For example, the constituent material of theadhesive layer 118 may be compressible. The adhesive layer 118 may bemade up of a plurality of layers including a cushion layer interposedbetween the upper layer and the lower layer of the adhesive material,for example, polyolefin foam. The adhesive layer 118 may be disposed onat least one of an upper surface and a lower surface of the extendedbody portion of the support layer 116.

The FPCB may be formed on the upper surface of the flexible substrate110. As another example, the FPCB may be bent and connected to the pad135 disposed on the opposite side of the active layer 101.

The micro coating layer 360 may be disposed to protect the wiring on theflexible substrate 110 and the like. For example, the micro coatinglayer 360 may be disposed across the entire bending area BA, forsufficient protection of the wiring, to start from the vicinity of thedriver IC and come into contact with the bottom surface of the touchelectrode layer 181 including the top surface of the active layer 101. Aportion of the micro coating layer 360 may be disposed to contact oradjoin the side surface of the touch electrode layer 181 by over-coatingat the end point of coating or by the surface tension between the touchelectrode layer 181 and the micro coating layer 360. The micro coatinglayer 360 may be formed in the entire region extending from the adjacentarea of the driver IC through the bending area BA to the active layer101, and as described in FIG. 1 , may be disposed along the notch 151line formed over the inactive region IA and the bending area BA.

FIG. 5 shows a sequence of steps in which oxides are produced in thefirst wiring 310. The flexible substrate 110 used as the substrate mayuse polyimide as described above. The polyimide contains a large amountof OH— fume in it, and the OH— fume can be released to the outside inthe process of coating and curing for the flexible substrate 110. Asdescribed above, for maintaining a smooth bending process and itsbending state, the wirings in the bending area BA may be formed bydepositing a threefold layer of titanium-aluminum-titanium (Ti—Al—Ti),which is a metal for source-drain, without a separate inorganicinsulating layer on the flexible substrate 110. For example, in order toform the first wiring 310 in the bending area BA, a source-drain wiringmay be formed simultaneously with the active area AA on the flexiblesubstrate 110, and through a photolithography process, photoresistcoating, photolithography, and development processes may be performed sothat a chain-shaped first wiring 310 remains. At this moment, a TiOxfilm may be formed between the flexible substrate 110 by a reaction ofOH— fume released from the flexible substrate 110 and Ti component oftitanium-aluminum-titanium (Ti—Al—Ti). When dry etching is performed toform a pattern of the first wiring 310, plasma chlorine gas (Cl) may beused. For example, the source-drain wiring and the photoresist may beremoved to form a shape of the first wiring 310, for which a dry etchingprocess may be performed. The dry etching process may be performed insuch a way that chlorine gas (Cl gas) is made into plasma in a vacuumchamber and the plasma chlorine molecules is then accelerated onto thesubstrate to remove the source-drain wiring and the photoresist. Theetching may be used in both wet etching and dry etching, but the dryetching will have an advantage of less impurities after the etchingprocessing. When the first wiring 310 is patterned, TiOx already formedmakes part of chlorine gas (Cl) remain on the surface of TiOx. Chlorinegas (Cl), moisture (H2O) in the atmosphere, and aluminum (Al) of thefirst wiring 310 react to generate hydrogen chloride (HCl) and aluminumoxide (Al2O3). It was confirmed that the reaction between aluminum andhydrogen chloride increased in a wide space between the wirings in thebending area BA. For example, it was confirmed that the larger thedistance or space between the wirings is, the more the oxidation of thesource-drain wiring increases. As such an interaction may continue, thegeneration of the aluminum oxide (Al2O3) around the first wiring 310 mayincrease, and the aluminum oxide (Al2O3) gradually grows to become adark spot. When the growth of the dark spot continues, it may extend upto its neighboring first wiring 310 to often cause electrical short inthe first wiring 310 or encroach on the first wiring 310 with the darkspot generated, so that the wiring may happen to lose its function orget disconnected.

FIG. 6 shows a plan view of the portion at which the bending area ofFIG. 4 begins. The low potential voltage wiring 126, the high potentialvoltage wiring 121, the gate power supply line 125, and the data wiring127 may be arranged in the bending area BA, of which wirings the datawiring 127 is taken as an example. The reason why the data wiring 127 istaken as an example is that although various wirings may be arranged inthe bending area BA, the data wiring 127 should be matched with thelight emitting device 112 disposed in the active area AA, so the largestnumber of wirings have to be formed in bending area BA. The data wiring127 should be formed in the bending area BA to transmit data signalsfrom the driver IC to the array 111 and the light emitting device 112 inthe active area AA. Hereinafter, it will be described considering thedata wiring 127 disposed in the bending area BA as the first wiring 310.The first wiring 310 disposed in the bending area BA can improve thedurability by designing the wirings in various shapes so as to withstandtensile stress and contraction stress. For example, the wirings may beformed of various shapes such as an elliptical chain shape as shown inFIG. 5 , a rhombus chain shape, a shape with a hole formed in the centerof a straight wiring, and the like. The present disclosure describes theelliptical chain shape illustrated in FIG. 5 as an example, but theshape of the wiring is not limited thereto. The first wirings 310 havinga chain shape may be arranged to be spaced apart at a regular interval.For example, they may be disposed at a distance of about 100 μm,although not limited thereto. At least one dummy pattern 320 may bedisposed in a space between the first wirings 310 to minimize an areaexposed without the first wiring 310 on the flexible substrate 110. FIG.6 illustrates that a plurality of two dummy patterns 320 in arectangular shape are disposed, side by side, along the first wiring310, but the arrangement is not limited thereto. Occurrence of oxidationin the first wiring 310 can be prevented by arranging the dummy patterns320 in an interval or space between the first wirings 310 and itsneighboring first wiring 310. Although it is described that the dummypattern 320 has a rectangular shape as an example, a polygonal shape, acircular shape, or an elliptical chain shape same as the first wiring310 would be also possible, but the shape is not limited thereto. Inorder to protect the first wiring 310, a crack stopper structure 126 maybe disposed between the first wiring 310 and the notch 151 which is acut surface of the substrate. Although FIG. 6 does not separately showany dummy pattern 320 outside the first wiring 310 disposed on theoutermost side, an additional dummy pattern may be disposed between thecrack stopper structure 126 and the first wiring 310. In the bendingarea BA, the first wiring 310 may have an elliptical chain shape, butwhen it extends to the inactive region IA, the first wiring 310 may havea straight structure. The shape of the wiring in the active region AAand the inactive region IA has a linear shape, but the shape of thewiring in the bending region BA may have an elliptical chain shape, arhombus chain shape or zigzag form, etc. so as to withstand contractionstress and tensile stress. The present disclosure describes an exampleof the elliptical chain shape of wiring, but the shape of wiring is notlimited thereto.

FIG. 7 is a view showing a cross-section of cutting line in FIG. 6 . Thefirst wiring 310 and the dummy pattern 320 may be disposed on theflexible substrate 110 without a separate insulating layer. AlthoughFIG. 7 shows two wirings 310 each having an elliptical chain-shapedcutting surface appear to be spaced apart from each other, they may bereferred to as a connected structure when seeing the plan view of FIG. 6. Further, the dummy patterns 320 are disposed to be spaced apart fromeach other by a predetermined distance D2 from one end of the firstwiring 310, between the first wirings 310. The first wiring 310 may bespaced apart from its neighboring first wiring 310 by a predetermineddistance D1. In this aspect, the distance D1 between the first wirings310 is assumed to be about 100 μm, but it is not limited thereto. In theaspect of the present disclosure, the distance D2 between the firstwiring 310 and the dummy pattern 320 is assumed to be about 17 μm. Theinventors of the present application have conducted various experimentsto identify the condition that the first wiring 310 is not oxidized. Forexample, in order to reduce the area where the flexible substrate 110 ofthe bending area BA is exposed, an experiment was performed in which thedummy pattern 320 is disposed as close as possible to the first wiring310. An experiment was conducted to apply various shapes of the dummypatterns 320 such as, for example, an elliptical chain shape or a zigzagshape, etc., so as to dispose the dummy patterns 320 closer to the firstwiring 310, while considering the shape of the first wiring 310 in thebending area BA. It was then confirmed that when the distance D2 betweenthe first wiring 310 and the dummy pattern 320 becomes less than 17 μm,an interaction may occur between the first wiring 310 and the dummypattern 320, thereby generating corrosion in the first wiring 310.Further, it was also confirmed that when the distance D2 between thefirst wiring 310 and the dummy pattern 320 is gradually increased from17 μm to 20 μm and further, up to 25 μm, the oxidation phenomenonbetween the first wiring 310 and the dummy pattern 320 increases.Accordingly, the dummy pattern 320 disposed between the first wire 310and its neighboring other first wire 310 may be disposed to be spacedapart from each other by about 17 μm.

The display apparatus according to an exemplary aspect of the presentdisclosure may include a liquid crystal display device (LCD), a fieldemission display device (FED), and an organic light emitting displaydevice (OLED), a quantum dot display device and the like.

The display apparatus according to an exemplary aspect of the presentdisclosure may be construed to include a set electronic apparatus, a setdevice or a set apparatus, such as a laptop computer as a completeproduct or a final product inclusive of a liquid crystal module (LCM),an OLED module or the like; a television; a computer monitor; anequipment display apparatus inclusive of an automotive display apparatusor a different form of vehicle; a mobile electronic apparatus such as asmartphone or an electronic pad, etc.

The display apparatus according to an exemplary aspect of the presentdisclosure may be described as follows.

The display apparatus according to an exemplary aspect of the presentdisclosure may include a flexible substrate having an active area and aninactive area, the inactive area including a first area adjacent to theactive area, a second area in which a pad is disposed, and a bendingarea disposed between the first area and the second area, wherein aplurality of wirings extending from the second area to the first areamay be disposed in the bending area, and a dummy pattern may be disposedbetween the plurality of wirings.

In the display apparatus according to an exemplary aspect of the presentdisclosure, at least two dummy patterns may be disposed, and the twodummy patterns may be spaced apart from the wiring at a regularinterval.

In the display apparatus according to an exemplary aspect of the presentdisclosure, a plurality of wirings may be spaced apart from each otherat a first interval, and at least two or more dummy patterns may bespaced at a second interval.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the plurality of wirings disposed in the bending area mayinclude a bending upper wiring and a bending lower wiring.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the plurality of wirings and dummy patterns may have anextended form of an elliptical chain.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the first interval may have a distance of at least 5 timesthe second interval.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the bending area may further include a crack stopperstructure in the vicinity of the outermost first wiring.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the dummy pattern may be spaced apart from the first wiringby a second distance, and may extend to the first area and the secondarea along the first wiring.

The display apparatus according to an exemplary aspect of the presentdisclosure may further include a crack stopper structure adjacent to thebending upper wiring and the bending lower wiring disposed at theoutermost part of the bending area.

In the display apparatus according to an exemplary aspect of the presentdisclosure, the cross-sectional width of a first wiring may be smallerthan that of a contact portion.

In the display apparatus according to an exemplary aspect of the presentdisclosure, a first organic insulating layer may be disposed between thefirst wiring and a second wiring, and a second organic insulating layerand a micro coating layer may be disposed on the second wiring.

The display apparatus according to an exemplary aspect of the presentdisclosure may have at least one crack stopper structure adjacent to thefirst wiring and the second wiring disposed at the outermost part of thebending area.

What is claimed is:
 1. A flexible display apparatus comprising: aflexible substrate having an active area and an inactive area, whereinthe inactive area includes a first area adjacent to the active area, asecond area in which a pad is disposed, and a bending area disposedbetween the first area and the second area; a data line, a portion ofwhich extends across the inactive area and comprises a first sub-portionextending in a first direction and a second sub-portion extending in asecond direction at a first predefined angle to the first direction; alow potential voltage line, a portion of which extends across theinactive area and comprises a first sub-portion extending in the firstdirection and a second sub-portion extending in a third direction at asecond predefined angle to the first direction; and a high potentialvoltage line, a portion of which is located in the inactive area andextends in the third direction, wherein in the inactive area, theportion of the data line partially overlaps at least one of the portionof the low potential voltage line and the portion of the high potentialvoltage line.
 2. The flexible display apparatus of claim 1, furthercomprising a dummy pattern disposed in the bending area, wherein thedummy pattern is disposed between a plurality of data line comprisingthe data line in the bending area.
 3. The flexible display apparatusaccording to claim 2, wherein the dummy pattern comprises at least twodummy patterns spaced apart from the plurality of data lines.
 4. Theflexible display apparatus according to claim 3, wherein the pluralityof data lines are spaced apart from each other by a first interval, andthe at least two dummy patterns are spaced apart from each other by asecond interval.
 5. The flexible display apparatus according to claim 4,wherein the first interval has a distance of at least 5 times the secondinterval.
 6. The flexible display apparatus according to claim 3,wherein the plurality of data lines and the at least two dummy patternshave an extended elliptical chain.
 7. The flexible display apparatusaccording to claim 3, wherein the plurality of data lines and the atleast two dummy patterns include a same material.
 8. The flexibledisplay apparatus according to claim 3, wherein the at least two dummypatterns extend in a same direction as the plurality of data lines. 9.The flexible display apparatus of claim 1, further comprising: anelectrostatic discharge circuit disposed in the first area of theinactive area; and an a gate-in-panel circuit disposed along an edge ofthe active area.
 10. The flexible display apparatus of claim 9, whereinthe electrostatic discharge circuit is disposed between bending area andthe gate-in-panel circuit.
 11. The flexible display apparatus of claim9, further comprising a gate power line, a portion of which extendsacross the first area of the inactive area and comprises a firstsub-portion extending in the third direction and a second sub-portionextending in a forth direction at a third predefined angle to the firstdirection.
 12. The flexible display apparatus of claim 11, wherein thegate power line overlaps the electrostatic discharge circuit.
 13. Theflexible display apparatus of claim 9, wherein the electrostaticdischarge circuit is located in a place in which a first line alongwhich the gate-in-panel circuit extends in the first direction and asecond line along which the high potential voltage line extends in thethird direction meet each other.
 14. The flexible display apparatus ofclaim 1, wherein the flexible substrate comprises a polyimideresin-based material.
 15. The flexible display apparatus of claim 1,further comprising a crack stopper disposed along an edge of theinactive area.
 16. The flexible display apparatus of claim 18, furthercomprising an a gate-in-panel circuit disposed along an edge of theactive area, wherein a portion of the crack stopper disposed in thefirst area of the inactive area is located outside of the gate-in-panelcircuit.
 17. The flexible display apparatus of claim 1, wherein theportion of the high potential voltage line is located between the activearea and the bending area.
 18. The flexible display apparatus of claim1, further comprising: at least one insulating layer disposed over theflexible substrate; and a coating layer disposed over the at least oneinsulating layer in the bending area.
 19. The flexible display apparatusaccording to claim 1, wherein the data line disposed in the bending areaincludes a bending upper line and a bending lower line.
 20. The flexibledisplay apparatus according to claim 19, further comprising a crackstopper structure disposed adjacent to the bending upper line and thebending lower line disposed at an outermost portion of the bending area.